The present invention relates to a timepiece comprising a 0 to 12 hours display, a minutes display, a time zone display for two geographical locations situated in two time zones separated by 180xc2x0 from one another, corresponding to the hours displayed by the said hours display, an AM/PM display for distinguishing between the hours preceding and those following the crossing of the meridian by the sun, an indicator for indicating for which of the two time zones displayed the hours are those before or after the crossing of the meridian, stepwise drive members for the moving elements of the said hour display and AM/PM indications and a rocker for the simultaneous correction of the hour display, time zone display and AM/PM indicator, capable of moving between two limit positions, and held in one of the said limit positions by a restoring spring.
There are several sorts of mechanisms for selectively displaying the time as a function of the time zone in which one finds oneself. Thus, FR 2 752 628 relates to a watch of this type in which the hours are displayed both by a hand and by a disc which indicates the local hours corresponding to those of the various cities, on a 24-hour scale. The cities representative of the various time zones are borne by a rotary disc. A correcting mechanism, intended for going from one time zone to another, links the 24-hour disc, the time zone disc bearing the indication of the cities and the time signalling in such a way as to make the cities disc and the hours disc perform {fraction (1/24)}th of a revolution with each correction.
Such a system makes it possible to ascertain the local time of the various locations on the planet by looking at the 24-hour disc and the corresponding cities. One of the drawbacks of such a mode of display arises from the fact that in most of the countries of the world, especially in all English-speaking countries, people are not accustomed to counting the hours of the day over 24 hours. Even in other countries, generally, the common parlance is to speak more easily of 2 PM rather than 14 hours for example, so that a watch displaying the hours on a 24-hour scale does not give a universally standard indication, even if it is comprehensible.
Another drawback arises from the fact that with a division into 24 time zones, the angular space is only 15xc2x0, so that in the case of a wristwatch, the indications of the cities belonging to the respective time zones is extremely constricted and consequently the indications must be written in very small characters and are therefore difficult to read.
However, the major drawback of the known systems arises essentially from the correcting mechanism. Specifically, when changing time zone, it is necessary to press a correcting pusher to move the hours indication and the time zone indication. The cinematic link in the known mechanisms is obtained through wheels and levers. The correction results directly from the pressure exerted on the correcting pusher controlling a rocker designed to drive the entire cinematic chain intended for the simultaneous correction of two indicators, that for the hour and that for the time zone.
In actuating conditions which are certainly incorrect but nevertheless possible, it may happen that just one of the two indicators is corrected, then inducing an error in the display of the time in the time zones as a whole. If such an error occurs, it is not then possible to correct it via the time zone correcting pusher. One is then compelled to correct it via the winding and time-setting stem, so losing the advantages of fast correction by pusher. This error results in fact from incomplete pressing of the correcting pusher. Specifically, the correction resulting directly from the travel of the pusher, it is always possible that now and again a user may not exert sufficient pressure for the simultaneous correction to occur. Even if this risk is small, it has an adverse consequence in so far as it cannot be corrected other than via the winding stem.
The aim of the present invention is to remedy, at least partly, the abovementioned drawbacks.
Accordingly, the subject of the present invention is a timepiece of the abovementioned type, as defined by claim 1.
The essential advantage of the solution proposed by this invention lies in the fact that the correction does not result directly from the pressure exerted on the correcting pusher, but that it is produced via the tightening of the restoring spring and only if this tightening is complete, that is to say if the finger of the correcting rocker is dislodged from the toothing, in which it is engaged, of the stepwise drive member for driving the moving elements of the display, going past a tooth of this toothing. If the pressure on the pusher is incomplete and if the finger of the rocker does not go past the tooth of the toothing of this member for the stepwise driving of the moveable elements of the display, the restoring spring relaxes without driving the drive member and without any correction occurring. In this case, the user will immediately realize that no correction has been made and he will merely need to press the pusher further down in order for the correction to be made. Therefore, no accidental offset between the display of the time and the indication of the time zone can occur following the actuation of the correcting pusher. Another advantage arises from the fact that the hours are displayed on a twelve-hour scale and two time zones 180xc2x0 apart are displayed simultaneously, the AM/PM display and the indicator showing the zone to which these AM/PM indications relate, makes it possible to avoid any error in the reading of the time indications without having to resort to a 24-hour scale.